Radio receiving circuits



July 3, 1928.

c. L. VOLZ RADIO RECEIVING CIRCUITS Filed Sept. 22, 1926 mm Q 8 hllllla INVENTOR.

[me/4' A .1442

ATTORNEY.

Patented July 3', 192.8.

1 UNITED STATES 1,675,473 PATENT OFFICE.

CHRIS L. VOLZ, OF DETROIT, MICHIGAN.

RADIO RECEIVING CIRCUITS.

Application as September 22, 1926. Serial No. 137,024.

This invention relates to radio receiving circuits and the object of the invention is to provide a radio receiving circuit arranged to produce the maximum power from each .5 stage of radio frequency amplification.

Another object of the invention is to provide a radio receiving circuit in which a condenser is connected across the secondary of each radio frequency transformer and adaptf 10 ed to feed back into the input of the previous radio frequency stage. 1

Another object of the invention is to provide a radio receiving circuit in which the output of the radio frequency transformers 15 is divided, a portion of thecurrent being fed into the input circuit of the preceding stage of radio frequencyamplification. A further object of the invent-ion is to provide a means for balancing the radio 20 frequency stages so that more than the usual two stages of radio frequency amplification may be utilized with the same purity of reproduction and with the additional power I attained by the extra stages.

These objects and the several novel features of the invention are hereinafter more fully described and claimed and the preferred form of construction by which these objects are attained is shown in the accom- 30 panying drawings in which- The figure is a. schematic diagram of a' radio receiving circuit embodying my invention.

As shown in the drawing a primary coil 35 1 of a. radio frequency transformer is connected directly in the antennae circuit. The secondary coil 2 is tuned by a variable condenser 3 and the input circuit 4; leads from the secondary coil 2 to the grid 5 of a vacuum 40 tube 6. The output circuit 7 for the vacuum tube is connected to the plate 8 of the vacuum tube and leads to the primary coil 9 of the second radio frequency transformer. The secondary 10 of this transformer is tuned 4 by the variable condenser 11. A three plate condenser 12 is connected across several of the turns of the secondary coil 10 and the central plate of this condenser is connected by means of a wire 13 to the input circuit 50 4 of the vacuum tube 6 as shown. The input circuit 14 for the vacuum tube 15 is connected at one end to the secondary coil 10 and at the opposite end to the grid 16 of the vacuum tube 15. The output circuit 17 for 5:5 the vacuum tube 15 is connected to the plate 18 at one end and to the primary coil 19 of the succeeding radio frequency transformer at the opposite end. The secondary coil 20 of this transformer is tuned by means of the variable condenser 21 and a three plate fixed condenser 22 is connected across several of the turns of the secondary coil 20 as shown on the drawing. The central plate of the fixed condenser 22 is connected by means of a circuit 23 to the input circuit 14 of the vacuum tube 15. Theinput circuit 24 for the vacuum tube 25 is connected at one endto the secondary coil 20 and at the opposite end to the grid 26 of the vacuum tube 25. The output circuit 27 for this vacuum tube is con- "nected at one end to the plate28 and at the opposite end to the primary coil 29 of the.

next radio frequency transformer. The secondary coil 30 of this transformer is tuned by means of a variable condenser 31. A three plate fixed condenser 32 is connected across several turns of the secondary coil 30 and the circuit 33 leads from the central plate of the condenser 32 to the input circuit 24. for the vacuum tube 25. This input circuit 34 for the vacuum tube 35 is connected to the secondary coil 30 and passes through the grid leak 36 to the grid 87 of this vac uum tube. The vacuum tube 35 is the de tector tube and the plate 38 thereof may be directly connected to a sound reproducing device 39 as shown or this output circuit may pass through an audio frequency amplifier before passing into the sound reproducing device.

The B battery 40 may be connected in the circuit as shown to supply plate voltage for the several vacuum tubes and the A battery 11 may be connected in the circuit as shown for lighting the filaments of the vacuum tube and rheostats 12 and 43 may be provided for controlling the filament voltages.

In this circuit the amount of feed back for a given frequency is arrived at by adjusting the three plate condensers 12, 22 and 32 and-should correspond to the average tube internal capacity. These condensers are of surplus capacity in construction and when i twenty-one turns of the secondary and in this circuit a variable reactance is set up by the winding and this outer plate condenser circuit is taped by a center plate on which a proper amount of currentis collected for the feed back. 111 this circuit-the phase relation of grid to plate capacity is opposed in the feed back and dilfersby one hundred and eighty degrees.

'VVith' this arrangement of balancing the circuit it is possible to use three stages of radio frequency amplification without distortion and with the clarity and faithfulness of reproduction of the usual two stages ofradio frequency amplification. By providing three stages of radio frequency amplification, together with this arrangement which prevents distortion, a very sensitive circuit is provided which is very efficient in receiving over long distances.

From the foregoing description it becomes evident that the circuit is very simple and efiicient in operation, is carefully balanced v by means of the fixed condensers which feed back into the input circuit of the previous stages and providesa device which accomplishes the objects described.

Having thus fully described my invention, its utility and mode of operation, what I claim-and desire to secure by Letters Patent of the United'States is- .1. A radio receiving circuit comprising :1

and a radio frequency transformer connecting ithestages, a three-plate fixed condenser connected across several of the turns of the secondarywif each radio frequency transformer, the central plate of each fixed condenser beingconnected to the input circuit of the preceding stage. I

2. A radio receiving circuit comprising a series of stages oftransi'ormer coupled radio frequency amplification, a three-plate condenserconnect-ed across several of the turns of each transformer secondary, the central plate-of each condenser being connected to the input circuit of the preceding stage.

"3. A radio receiving circuit comprisin a series ofstages of radio frequency amplification each including a vacuum tube, a radio frequency transformer having a primary connected to the outputicircuit of one stage and a secondary connected to the input circuit of the succeeding stage, a three ,plate fixed condenser having the two outer plates connected across several of the turns of the secondary winding and a central plate connected to the input circuit of the preceeding stage.

In testimony whereof I sign this specification.

CHRIS L. VOLZ. 

